Commit c3ca8a0a authored by Claudiu Beznea's avatar Claudiu Beznea Committed by Greg Kroah-Hartman
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serial: sh-sci: Check that the DMA cookie is valid 



The driver updates struct sci_port::tx_cookie to zero right before the TX
work is scheduled, or to -EINVAL when DMA is disabled.
dma_async_is_complete(), called through dma_cookie_status() (and possibly
through dmaengine_tx_status()), considers cookies valid only if they have
values greater than or equal to 1.

Passing zero or -EINVAL to dmaengine_tx_status() before any TX DMA
transfer has started leads to an incorrect TX status being reported, as the
cookie is invalid for the DMA subsystem. This may cause long wait times
when the serial device is opened for configuration before any TX activity
has occurred.

Check that the TX cookie is valid before passing it to
dmaengine_tx_status().

Fixes: 7cc0e0a4 ("serial: sh-sci: Check if TX data was written to device in .tx_empty()")
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarClaudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Link: https://patch.msgid.link/20251217135759.402015-1-claudiu.beznea.uj@bp.renesas.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f5415114

drivers/tty/serial/sh-sci.c

+1 −1
Original line number Diff line number Diff line
@@ -1914,7 +1914,7 @@ static void sci_dma_check_tx_occurred(struct sci_port *s) 
	struct dma_tx_state state;

	enum dma_status status;



	if (!s->chan_tx)

	if (!s->chan_tx || s->cookie_tx <= 0)

		return;



	status = dmaengine_tx_status(s->chan_tx, s->cookie_tx, &state);